Sphingomonas lenta sp. nov., a slowly growing bacterium isolated from an abandoned lead-zinc mine.

A novel slowly growing member of the genus Sphingomonas, designated 1PNM-20, was isolated from an abandoned lead-zinc mine in Meizhou, Guangdong Province, PR China. A polyphasic taxonomic study was performed to characterize the novel strain. Growth occurred on Reasoner's 2A (R2A) agar and peptone-yeast extract (PYE) agar, but not in liquid R2A or PYE media. Cells were Gram-stain-negative, aerobic, non-spore-forming, rod-shaped and motile with a polar flagellum (monotrichous). 16S rRNA gene sequence comparison showed that it shared the highest similarity with Sphingomonas carriPR0302 (97.2 %), followed by Sphingomonas spermidinifaciens 9NM-10 (97.0 %), Sphingomonas floccifaciens FQM01 (97.0 %) and other species of Sphingomonas (<97 %). Phylogenetic analyses clearly showed that strain 1PNM-20 fell into the cluster of Sphingomonas, and was most closely related to S. carri. The draft genome sequence was 3.76 Mb in length with a DNA G+C content of 69.8 mol%. Major fatty acids were summed feature 8 (C18 : 1ω7c and/or C18 : 1ω6c), summed feature 3 (C16 : 1ω7c and/or C16 : 1ω6c), C16 : 0 and 11-methyl C18 : 1ω7c, with C14 : 0 2-OH as the main hydroxy fatty acid. Ubiquinone 10 (Q-10) was the predominant respiratory quinone, and sym-homospermidine was displayed as the major polyamine. The polar lipids were composed of sphingoglycolipid, phosphatidylglycerol, diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylcholine, an unidentified phospholipid and an unidentified glycolipid. The phenotypic, phylogenetic and chemotaxonomic results supported the hypothesis that strain 1PNM-20 represents a novel species of the genus Sphingomonas, for which the name Sphingomonas lenta sp. nov. is proposed. The type strain is 1PNM-20 (=GDMCC 1.660=DSM 27572).